Almost a third of Americans believe obese and overweight individuals should be penalized for their lifestyle, according to an NPR poll released Thursday.

NPR asked participants if overweight and obese people should pay more for health insurance. The poll also found the same number of people thought smokers should pay more for their healthcare.

Participants said the main contributors to health insurance costs were smoking (28.5 percent), obesity (27.6 percent) and stress (25.2 percent)

Nearly 85 percent of those polled said people who engage in healthful practices like exercise and smart diet should see a reduction in healthcare costs.

"Discounts for good behaviors are always more popular than surcharges for bad behaviors, but the science of behavioral economics teaches us that loss avoidance is three times more powerful than receiving a gain," said Raymond Fabius, M.D., chief medical officer for the healthcare business of Thomson Reuters, in the press release.

"Before anyone rushes to create behavior-based plans, though, it's important to look at the data. Our research shows that obesity is a much higher driver of healthcare costs than smoking."

Over a third of Americans are clinically obese, according to recent data. The number has been on the steady rise for decades.

Smokers, on the other hand, are in sharp decline. Only 21 percent of Americans identify themselves as smokers. This number is down from 45 percent in the 1950s.

One out of 10 people polled said they thought it was acceptable to deny employment to overweight and obese individuals, according to the poll.

Obesity and overweight issues have come to a head recently, amongst reports of weight discrimination in various environments including certain airlines requiring overweight passenger to purchase two tickets for safe travel.

Many of the respondents who said the overweight should be charged extra for health costs were college-educated and had incomes over $100,000.

Thomson and Reuters conduct polls monthly to gauge public opinion on health-related issues.